It is known from the state of the art to provide mobile electronic systems with a two dimensional compass. Such a mobile electronic system may be included for instance in a communication device like a mobile phone.
In German patent application DE 198 37 568 A1, it is proposed to provide a Personal Digital Assistant (PDA) with a Global Positioning System (GPS) receiver, a mobile communication unit and a compass. The compass is used for determining the current orientation of the PDA, which is required for realizing navigation functions in the PDA.
In British patent application GB 2 298 539 A, it is equally proposed to provide a hand held device containing a GPS receiver with a compass. A displayed information relating to the current environment, e.g. a map, is rotated in accordance with the respective orientation of the device.
Further, it is proposed in international application WO 01/88687 A2 to access context information with a user equipment, e.g. a mobile phone. The context information is downloaded from a network based on a location service. Then, the orientation of the user equipment is determined using a compass in the user equipment. Once the orientation is known, a visual user interface is generated at the user equipment for displaying the downloaded context information. In order to select a virtual object displayed in the visual user interface, the user can point to the respective object by orienting the user equipment. During the movement of the user equipment, the displayed virtual objects move accordingly in front of the user.
A mobile electronic system may also comprise an Inertial Navigation Systems (INS), which INS can be used for determining the position of the mobile electronic system. In such a system, it is essential that provided heading information remains accurate along time, since even small errors in the computed orientation cause significant errors to the position estimate. Traditionally, IN Systems utilize gyro-compasses to ensure an accurate heading. Gyro-compasses, however, have several disadvantages. They constitute quite expensive components due to their complicated electronics. Moreover, they are physically large sensors and can thus not be implemented in small modules. The use of a conventional 3-axis gyro-compass in a small INS is not feasible at all, since it requires even more complex electronics and its power consumption is much higher. As a result, it is more expensive and it also requires more space. A 3-axis operation, however, is essential for an accurate INS.